Until some weeks ago I was still using my trusty Fujitsu T4210/15 as my main mobile computer and the TC4400 slate I built myself also saw some use from time to time. But the hinge of the T was obviously starting to show its age after more than half a decade of heavy use and abuse. The latter from me as much as likely from the previous owner. Trying to keep it alive was tried with different ways.

How to lube a Tablet PC hinge?

Classic lithium based grease and WD40 have both failed to act as a suitable lubricant for the hinge construction inside the display housing that is responsible for the opening and closing process. MoS2 grease wasn’t good either. The sound it made when moved with either of those was a little frightening to say the least. The thing that finally made it silent and feel good again was some bicycle chain oil I had lying around. Less watery than WD40 (here in DE WD40 is mainly petroleum, US WD40 might work well) and less solid than any of the other greases, while also being quite adhesive. None the less you could feel that the whole hinge construction was nearing the end of its useful lifetime under the conditions I exposed it to. So I decided to look for a successor and give it to my GF, who should have another year or two of fun with my T.

What to get now?

But what to get? It had to be a Tablet PC again. Normal laptop was not worth considering, annotating PDFs and using OneNote for all kinds of scribbling is way to convenient once you are used to it. A pure slate without a keyboard also was no choice. Handwriting recognition is really good, but its weakpoint to me is recognizing symbols and combinations unusual in normal language. Besides this is way slower than typing.

I looked around for some time and in the end the best bang for the buck was the very same ebay seller selling the very same TC4400 I had recommended to so many people. So I now have not just a TC4400 Slate, but also a normal TC4400. Getting was a ibt of a hassle as the first one I got was way worse then described, but after some encouraging calls I ended up with one that essentially looks brand new. No visible use of the keyboard or trackpad. The backlight also seems to be in a good condition (it’s CCFL, so gets dimmer and shifts color to a rose tint over time) and no scratches or signs of actual use anywhere. The only thing you can see and feel has been used a bit is the pen. What I paid? Including a secondary battery below 200€!

I thought long about getting something as old as this from a technology point of view. But in the end, I have no reason to buy anything newer as the additional performance from the CPU is not going to make it much faster and the other big point, battery life, also wouldn’t be substantially better unless I would buy something pretty recent. That would be roughly 5 times the money at least. For a real boost it would have to be Sandy Bridge which equals ~1400€+++, for essentially next to nothing.

How to hack it?

I’ve cursed this in the past and it has kept me from recommending or getting any Dell, IBM and HP hardware: BIOS whitelisting, blacklisting and all the like.

HP is big in this game, too. If you scroll back a lot here to the early days of this blog, you’ll find an article describing how I got around HP’s damned branding of a Wifi Link 5100 by rewriting the device ID and subsystem ID. They take normal hardware and have it customized with changes useless besides making it incompatible. And then they sell “their” cards for five times what the generic version is worth. Of course you can’t upgrade your Wifi too far even when buying their crap, better get something entirely new.

So yeah, the TC4400 of course also has BIOS whitelisting and refuses to take that very same Wifi Link 5100. Well, refused. I googled a lot and got into a thread on some forum where people where quite eagerly deciphering and reverse engineering BIOSes and among that was one for an NC4400, which is essentially the exact same with a different hinge and without a digitizer. After some time of delving into the topic I thought this should be doable. In addition I found out that there are ways to restore a bad BIOS flash easily, without desoldering anything or using JTAG. The damn thing can restore a bad BIOS flash from a USB diskette (!) drive.

It now happily accepts my Wifi Link 5100 and possibly anything else, too. I haven’t done too much myself, as I have to admit. I mainly ported a BIOS hack to a nearly identical other BIOS.

What the …?

I noticed a slight misbehavior of my newly acquired toy after its initial defloration, for replacing memory, wifi card and harddisk. The power light never goes out entirely. It merely gets slightly dimmer. Also, the battery gets drained about 5% per hour. In addition, when shut off or sleeping while connected to AC or a non empty battery it later shows very very weird symptoms on its LCD. On the left and right side entire horizontal lines of subpixels are constantly on, like dead pixels. On the upper and lower rim of the screen it’s just parts of the line. So a problem on the level of display memory or logic is out of the question, also it happens everywhere and is totally independent of picture content.

I have never seen this before. If you wait long enough those colored lines get more and ultimately the display has a border of too high brightness all around. How the fuck ?!?

Additionally there’s another quirk. If you disconnect AC and all batteries, inserting a battery will make it change its power state, rev up the fan but not show any image or do anything. You can switch it off again, but there’s no way to boot it. You have to insert the battery while it is on and connected to AC or a different battery.

Before you read on, try to guess what could cause this. Consider all you know about computers and their sometimes weird behavior. I would have never figured it out be mere thought if I would have been presented the laptop in this state. As I had changed CPU, HDD, wifi and memory in one go I tried to change back the parts piece by piece after being sure to have no explanation which one of those could cause this.

It was in fact the Wifi card. Once it is pulled the power LED does not stay on for no reason and also inserting a battery is not a problem anymore. I have not found the time to fix this or further investigate how this works, but someone else with a very similar problem has told me that isolating all of the mini PCIe card’s pins that are unused or NC according to some pinout he found did fix the problem for him. I would have tried the same as a first step.

So, yeah. Once I tape up the wifi card’s pins I should be done setting this thing up and can just use it.

Welcome to HackHut

HackHut is a free hosting service for hackers, DIYers, etc. to document their work. Each site in the network is independently run by its owner. Sign-up for your own site here on HackHut, and start documenting your hacks today completely free.